Suture anchors are often used for repairing a soft tissue, for example a muscle, a tendon or a ligament that has to be attached to a bone. When certain injuries take place, it is frequent that ligaments, tendons and other soft tissues are detached from the bones with which they are associated. Consequently, it becomes necessary to reattach the soft tissue to the bone in order to facilitate healing. The surgeon may have various devices for reattaching the soft tissue to the bone, such as screws, staples, pins, nails or even only a suture thread. A suture anchor can be anchored into the bone of the patient at the desired point of reattachment of the soft tissue, allowing a surgical suture thread to be attached. Such a suture anchor can be inserted into a bony cavity prepared for this purpose, or can be self-tapping.
After insertion into the bone, the anchor can be held in position by external elements, for example threading, ribs or excrescences of various types. These external elements provide a tension resistance so that the anchor is rigidly held in position during healing. Equally, such an anchor may comprise an eyelet, a bar, or another element for the attachment of the suture thread. Therefore, the free ends of the suture extend outside the bone, pass through or round the soft tissue and are used to attach the soft tissue to the bone.
However, certain known suture anchors, although effective in attaching a soft tissue to a bone, have a number of disadvantages. In practice, the anchor head may require sufficient dimensions to receive a driving tool, and to withstand the axial force and the torque generated by this driving tool when the anchor is inserted into the bone. Such an anchor has an increased length, and must be positioned in the bone at a sufficient depth to prevent the soft tissue from scraping against the exposed anchor head. However, once anchored, a tension applied to the anchor may cause it to migrate in the bone and cause the anchor head to come out of the bony cavity. This phenomenon of removal tension may cause a weakening of the attachment and a releasing of the soft tissues, and may even damage them. Moreover, the suture thread coming out of the anchor may rub against the edge of the bony cavity and be damaged.